Add introspection typesupport tests for C/C++ messages

[hidmic]

This patch generalizes the testing infrastructure in #641 to validate introspection APIs for both C and C++ interfaces.

[hidmic]

@j-rivero @gbiggs this is the HEAD of the work, including all other changes in this repository currently in PRs. I'll add a few more message tests tomorrow. Once all this is in, I'll work on a few service and action tests -- infrastructure shouldn't change much once we've settled with message tests.

[gbiggs]

I don't know the rosidl_runtime_* packages, so I've only looked at the rosidl_typesupport_introspection_* files.

[hidmic]

CI up to rosidl_typesupport_introspection_tests:

• Linux
• Linux-aarch64
• Windows

[hidmic]

@ros-pull-request-builder retest this please

[hidmic]

Windows CI after 6545f13:

• Windows

[j-rivero]

It is a really great work. I can not find any single obvious error with my level of knowledge. I leave some comments to improve and some clarifications.

[j-rivero]

We are reproducing the same code pattern for the sequence of "Array, BasicTypes, BoundedSequences, ..." in this file. Would be possible to somehow define the sequence in one place and iterate over it?

[hidmic]

Not sure I follow you here.

[j-rivero]

Sorry, let me explain it:

In https://github.com/ros2/rosidl/pull/651/files#diff-31e6f9e3f2b7b5c3a3250552def63bc483cbbcd37ccd184b226445523af638d1R82-R108 we are calling

 MESSAGE_TYPESUPPORT_SYMBOL_RECORD(
      rosidl_typesupport_introspection_c,
      rosidl_typesupport_introspection_tests, msg, $$VALUE$$),

Where $$VALUE$$ is in the list of "Array, BasicTypes, BoundedSequences, ...". Not sure if it would be possible to replace the duplication with a loop somehow.

Just below https://github.com/ros2/rosidl/pull/651/files#diff-31e6f9e3f2b7b5c3a3250552def63bc483cbbcd37ccd184b226445523af638d1R122-R205, for the traits we are doing the same by duplicating:

template<>
struct introspection_traits<rosidl_typesupport_introspection_tests__msg__Arrays>
{
  static constexpr const MessageTypeSupportSymbolRecord typesupport =
    MESSAGE_TYPESUPPORT_SYMBOL_RECORD(
    rosidl_typesupport_introspection_c,
    rosidl_typesupport_introspection_tests, msg, $$VALUE$$);
  using TypeSupportLibraryT = IntrospectionCTypeSupportTestLibrary;
};

Is not that I have something clear in mind to reduce the duplication, just asking. Feel free to drop if you no easy way.

[hidmic]

Oh I see.

Not sure if it would be possible to replace the duplication with a loop somehow.

These are compile time definitions, so looping isn't possible. We could add some variadic macros to recurse though. Duplication will go away but the macros are tricky.

for the traits we are doing the same by duplicating:

Right. Same answer. It is doable with variadic macros.

[j-rivero]

Thanks for the feedback, proposal was not a blocker for this PR.

[hidmic]

CI again:

• Linux
• Linux-aarch64
• Windows

[j-rivero]

LGTM with green in CI. We would need to document the issue with the actions to take care of it at some point. That we can done in new PRs.

[hidmic]

@j-rivero agreed. In fact, we should probably revisit action testing in this entire repo.